It sounds like something in your configuration is marked “Power Device” in a particular Activity when it actually applies to multiple Activities. Just unset that if you have a multi-activity device.
Roomie remembers whenever it sends a Power Toggle and tracks any device as to whether it is on or off. If you start the System Off Activity, Roomie knows not to send a Power Toggle to a device that is already off. It just ignores the command and doesn’t send it (unless you disable power tracking for a given device).